Imagine a pond, dotted with shiny floating leaflets that soak up sunlight and use the water below to produce clean fuels. That’s the vision of researchers at Cambridge University, who have made lightweight, flexible devices that imitate the way plants produce food via photosynthesis.
In outdoor tests on the river Cam in Cambridge, the low-cost artificial leaves could convert sunlight into fuels as efficiently as plant leaves, the team reports in the journal Nature. If the technology could be scaled up, it could be deployed on seas and on polluted waterways, producing fuel without taking up precious land resources, they write.
Scientists have been trying to mimic photosynthesis for many years with artificial leaf devices, which use sunlight to convert water and carbon dioxide into fuel.
In 2019, the Cambridge team, led by chemistry professor Erwin Reisner, made an artificial leaf that produces a chemical mixture called syngas. Syngas, a mix of carbon monoxide and hydrogen, is used to make fuels, pharmaceuticals, and fertilizers. The device used light-absorbing materials known as perovskites, along with a cobalt catalyst. But it was heavy and fragile, with the perovskites coated on glass.
To make portable and lightweight artificial leaves, the team has now deposited layers of perovskites and a platinum catalyst on thin plastic films. They covered these layers with water-repellant carbon-based materials to protect the devices against water damage.
The resulting artificial leaves float on water, splitting water into hydrogen and oxygen, and turning carbon dioxide into syngas. The device produces 0.58% of hydrogen and 0.053% of carbon monoxide for each gram of the material, an output comparable to natural leaves. The researchers made devices ranging in size from 1.7 cm2 up to 100 cm2, showing how the technology can be scaled up.
“We wanted to see how far we can trim down the materials these devices use, while not affecting their performance,” said Reisner in a press release. “If we can trim the materials down far enough that they’re light enough to float, then it opens up whole new ways that these artificial leaves could be used.”
Source: Andrei, V. et al. Floating perovskite-BiVO4 devices for scalable solar fuel production. Nature, 2022.